J. Indian Chem. Soc., Vol. 87, November 2010, pp. 1385-1389 NOTE Cyano complexes of oxotungsten(IV) with aroyl hydrazone ligands Mohd Saleem, Mollita Sharma, Simpy Mahajail, H. N. Sheikh* and B. L. Kalsotra Department of Chemistry, University of Jammu, Jammu-180 006, Jammu & Kashmir, India E-mail : hnsheikh@rediffmail.com Manuscript received 26 October 2009, revised 10 May 2010, accepted 17 May 2010 Abstract : Reactions of K 3 Na[W0 1 (CN) 4 ).611 1 0 with aroyl hydrazone ligands namely benzoic acid[l-(furan-2- yl)methylene]hydrazide (BFMll), benzoic acld[(thlophene-2-yl)methylene]hydrazide (BTMII), benzoic acid[l-(thiophenc- 2-yl)ethylldene)hydrazlde (BTEII), benzoic acld(phenylmethylene)hydrazide (BPMII) and benzoic ucid[l-(anlsol-3- yl)methylene]hydrazlde (BAM II)) In presence of acetic acid yield complexes of the type [WO(CN}JL-L)", The com111exes have been characterized by conductivity, magnetic susceptibility, IR, 1 11 NMR, UV-Vis and TGAIDTA studies. The ligunds substitute one water and one. cyanide group or the protonated K3Na[W02(CN) 4 ].6H 2 0 and bind In bidentate ehelatlng mode. The mode of bonding or the ligands Is confirmed by shirts observed in the •n NMR spectrum of the ligand after complexation. Keywords: Aroyl hydrazones, cya110 complexes, trlpheuyl phosphine imminium chloride, 1 H NMR, TGA/DTA. Introduction A series of oxo-cyano complexes of molybdenum(Iv) and tungsten(IV) with various monodentate ligands of fonnula [M(CN) 4 0(L)]n,., where L = Ncs-. N 3 -, F-, HCN and py (pyridine); M = Mo or W have been synthesised and characterised 1 -3. The protonation of the dioxotetracyano complexes of molybdenum(lv), rungsten(IV), rhenium(v), technetium(v) results in the formation of [MO(OH)(CN) 4 ]Cn+ll- and [MO(H 2 0)(CN)41°- complexes and have been studied in detail over the past decade 4 ·'. These protonated species undergo aqua substitution reac- · tions by monodentate ligands'· 7 and both aqua and cyano substitution by bidentate ligands8,9. The protonation behaviour of these systems has been the subject of C-13 and 0-17 NMR studies in order to investigate the water exchange of these complex ionsiO, The existence of protonated forms was duly established by means ofthe strucrure determination of [Cr(en) 3 ) [Mo0- (0H)(CN),J.H20, [Pt(enhJ [Mo0(H 2 0)(CN)41 2 .H 2 0 and (PPh 4 h[MoO(H 2 0)(CN) 4 ] .4H 2 0 11 • 12 . These structure determinations as well as the structural data of [Mo0 2 (CN),J4- showed that Mo=O and Mo-OH bonds are much stronger than the Mo-OH 2 bonds l3. It was found that the bidentate ligand 1,10-phenanthrolene (phen) re- acts with trans-[Mo0 2 (CN)414- resulting in the formation of [MoO(phen)(CN)Jr 14 • 1 s. This ground-state stabiliza- tion of the metal-oxygen bond on protonation indicates that it is actually protonated forms that are reactive to- wards substitution. This supposition was continned by the observation that no reaction occurred at a high pH where [Mo0 2 (CN) 4 ] 4 - is the main species. The fact that a cyano ligand was also displaced from the parent ion raised the question of which ligand (aqua, hydroxo or cyano) will first be substituted during a presumably two-step sub- stirution process with a bidentate ligand. The crystal struc- ture determination ofCs 2 Na[MoO(N 3 )(CN) 4 ] 1 6 clearly in- dicated that aqua ligand is preferentially substituted by the azide ligand. Complexes of the type [MO(L-L)(CN>J]<n+l)-, where L-L = 2,2' -bipyridyl (bipy), I, I 0-phenanthrolene (phen), pyridine-2-carboxylate (pic) and several Schiff bases and M = Mo or W have been studied in detaiJI?-22. The cyano complexes of Mo 1 V and w 1 V with organic ligands have found application in the study of solvation effects 17 • Hydrazones are an important class of organic com- pounds23-l6, some of which show significant biological activities. Moreover, in many cases, it has been suggested that some biological activities of organic compounds in- creased by the coordination with metals 27 . For example, ligand 3,4,5-triphenolbenzoyl salicylaldehyde hydrazone 1385